October 19, 2017

14.03.10-Record Lightning Storm Spotted by Cassini.

The shadow of Titan as viewed by Cassini. (Credit: NASA/JPL/Space Science Institute).

The shadow of Titan as viewed by Cassini. (Credit: NASA/JPL/Space Science Institute).


Saturn is turning out to be a very electrified place. Last year, NASA’s Cassini orbiter spied a massive storm that broke the solar system record; beginning in January 2009, this storm raged on for 7 ˝ months, the longest recorded. This marks the ninth storm on Saturn thus recorded; these behemoths tend to be around 1,900 miles in size. It’s been known since the initial Voyager flybys of the ringed world in the 1970’s that an ionization differential of x100 exists in favor of the daytime side of Saturn over its night side, but routine observations by Cassini are revealing what a turbulent world Saturn really is. Cassini utilizes its antennae aboard its Radio and Plasma Wave Science instrument to analyze the powerful radio emissions.   Tantalizingly, the storms almost always originate in a region known as “Storm Alley” at latitude 35° south. The reason for this isn’t entirely clear. Scientists also took advantage of a passage of Cassini behind Saturn’s largest moon, Titan, to confirm the source of these radio emissions. Surely enough, when Titan occulted the body of Saturn, the emissions disappeared, only to return when Saturn came back into view. This was yet another proof that Saturn is still an active and mysterious place.

23.10.09:Fermi Pegs Gamma-Ray Pulsars.

NASA’s Large Area Telescope aboard the orbiting Fermi gamma-ray observatory continues to turn out some amazing science, picking up where Compton left off in 2002 as it surveys the gamma-ray sky. Of particular interest are gamma-rays emitted from pulsars. Pulsars are the swiftly rotating remnants of massive stars that have gone supernova, leaving a superdense core in their wake. These are sometimes called “neutron stars” because the matter comprising them is packed so tightly the individual nuclei are literally stacked end to end, making a spoonful weigh as much as a mountain! After all, most ordinary matter is made of….nothing. A neutron star can be thought of as a large, singular atomic nucleus, again weird stuff. Most of the 1,800 pulsars thus detected are because of their copious radio emissions beaming from their poles. Thus, we have to be in the line of sight before we see their blinking radio pulsations. Enter Fermi, which has thus far spotted 16 new pulsars via their gamma-ray emissions alone. This promises to aid in identifying pulsars whose poles aren’t tipped to our line of sight, which are probably in the majority. But even the gamma-ray sky is relatively dim; for example, the Vela pulsar is one of the brightest in the sky, and it emits a mere 1 gamma-ray photon every 2 minutes! Initially dubbed “Little Green Men” (LGMs!) during their discovery in the 1960′s, pulsars were soon naturally explained, but still continue to amaze. Watch this space and the Fermi mission for news from the high energy end of the spectrum!